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2026 09:11:21 -0700 In-Reply-To: <69365d0c.a70a0220.38f243.0085.GAE@google.com> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <69c40929.a70a0220.234938.0053.GAE@google.com> Subject: Forwarded: Re: [PATCH v1] Bluetooth: hci_sync: Fix UAF in le_read_features_complete From: syzbot To: linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable For archival purposes, forwarding an incoming command email to linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com. *** Subject: Re: [PATCH v1] Bluetooth: hci_sync: Fix UAF in le_read_features_co= mplete Author: luiz.dentz@gmail.com #syz test On Wed, Mar 25, 2026 at 11:43=E2=80=AFAM Luiz Augusto von Dentz wrote: > > ---------- Forwarded message --------- > From: Luiz Augusto von Dentz > Date: Wed, Mar 25, 2026 at 11:18=E2=80=AFAM > Subject: [PATCH v1] Bluetooth: hci_sync: Fix UAF in le_read_features_comp= lete > To: > > > From: Luiz Augusto von Dentz > > This fixes the following backtrace caused by hci_conn being freed > before le_read_features_complete but after > hci_le_read_remote_features_sync so hci_conn_del -> hci_cmd_sync_dequeue > is not able to prevent it: > > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D > BUG: KASAN: slab-use-after-free in instrument_atomic_read_write > include/linux/instrumented.h:96 [inline] > BUG: KASAN: slab-use-after-free in atomic_dec_and_test > include/linux/atomic/atomic-instrumented.h:1383 [inline] > BUG: KASAN: slab-use-after-free in hci_conn_drop > include/net/bluetooth/hci_core.h:1688 [inline] > BUG: KASAN: slab-use-after-free in > le_read_features_complete+0x5b/0x340 net/bluetooth/hci_sync.c:7344 > Write of size 4 at addr ffff8880796b0010 by task kworker/u9:0/52 > > CPU: 0 UID: 0 PID: 52 Comm: kworker/u9:0 Not tainted syzkaller #0 PREEMPT= (full) > Hardware name: Google Google Compute Engine/Google Compute Engine, > BIOS Google 10/25/2025 > Workqueue: hci0 hci_cmd_sync_work > Call Trace: > > __dump_stack lib/dump_stack.c:94 [inline] > dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120 > print_address_description mm/kasan/report.c:378 [inline] > print_report+0xcd/0x630 mm/kasan/report.c:482 > kasan_report+0xe0/0x110 mm/kasan/report.c:595 > check_region_inline mm/kasan/generic.c:194 [inline] > kasan_check_range+0x100/0x1b0 mm/kasan/generic.c:200 > instrument_atomic_read_write include/linux/instrumented.h:96 [inline] > atomic_dec_and_test include/linux/atomic/atomic-instrumented.h:1383 [inl= ine] > hci_conn_drop include/net/bluetooth/hci_core.h:1688 [inline] > le_read_features_complete+0x5b/0x340 net/bluetooth/hci_sync.c:7344 > hci_cmd_sync_work+0x1ff/0x430 net/bluetooth/hci_sync.c:334 > process_one_work+0x9ba/0x1b20 kernel/workqueue.c:3257 > process_scheduled_works kernel/workqueue.c:3340 [inline] > worker_thread+0x6c8/0xf10 kernel/workqueue.c:3421 > kthread+0x3c5/0x780 kernel/kthread.c:463 > ret_from_fork+0x983/0xb10 arch/x86/kernel/process.c:158 > ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246 > > > Allocated by task 5932: > kasan_save_stack+0x33/0x60 mm/kasan/common.c:56 > kasan_save_track+0x14/0x30 mm/kasan/common.c:77 > poison_kmalloc_redzone mm/kasan/common.c:400 [inline] > __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:417 > kmalloc_noprof include/linux/slab.h:957 [inline] > kzalloc_noprof include/linux/slab.h:1094 [inline] > __hci_conn_add+0xf8/0x1c70 net/bluetooth/hci_conn.c:963 > hci_conn_add_unset+0x76/0x100 net/bluetooth/hci_conn.c:1084 > le_conn_complete_evt+0x639/0x1f20 net/bluetooth/hci_event.c:5714 > hci_le_enh_conn_complete_evt+0x23d/0x380 net/bluetooth/hci_event.c:5861 > hci_le_meta_evt+0x357/0x5e0 net/bluetooth/hci_event.c:7408 > hci_event_func net/bluetooth/hci_event.c:7716 [inline] > hci_event_packet+0x685/0x11c0 net/bluetooth/hci_event.c:7773 > hci_rx_work+0x2c9/0xeb0 net/bluetooth/hci_core.c:4076 > process_one_work+0x9ba/0x1b20 kernel/workqueue.c:3257 > process_scheduled_works kernel/workqueue.c:3340 [inline] > worker_thread+0x6c8/0xf10 kernel/workqueue.c:3421 > kthread+0x3c5/0x780 kernel/kthread.c:463 > ret_from_fork+0x983/0xb10 arch/x86/kernel/process.c:158 > ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246 > > Freed by task 5932: > kasan_save_stack+0x33/0x60 mm/kasan/common.c:56 > kasan_save_track+0x14/0x30 mm/kasan/common.c:77 > __kasan_save_free_info+0x3b/0x60 mm/kasan/generic.c:587 > kasan_save_free_info mm/kasan/kasan.h:406 [inline] > poison_slab_object mm/kasan/common.c:252 [inline] > __kasan_slab_free+0x5f/0x80 mm/kasan/common.c:284 > kasan_slab_free include/linux/kasan.h:234 [inline] > slab_free_hook mm/slub.c:2540 [inline] > slab_free mm/slub.c:6663 [inline] > kfree+0x2f8/0x6e0 mm/slub.c:6871 > device_release+0xa4/0x240 drivers/base/core.c:2565 > kobject_cleanup lib/kobject.c:689 [inline] > kobject_release lib/kobject.c:720 [inline] > kref_put include/linux/kref.h:65 [inline] > kobject_put+0x1e7/0x590 lib/kobject.c:737 > put_device drivers/base/core.c:3797 [inline] > device_unregister+0x2f/0xc0 drivers/base/core.c:3920 > hci_conn_del_sysfs+0xb4/0x180 net/bluetooth/hci_sysfs.c:79 > hci_conn_cleanup net/bluetooth/hci_conn.c:173 [inline] > hci_conn_del+0x657/0x1180 net/bluetooth/hci_conn.c:1234 > hci_disconn_complete_evt+0x410/0xa00 net/bluetooth/hci_event.c:3451 > hci_event_func net/bluetooth/hci_event.c:7719 [inline] > hci_event_packet+0xa10/0x11c0 net/bluetooth/hci_event.c:7773 > hci_rx_work+0x2c9/0xeb0 net/bluetooth/hci_core.c:4076 > process_one_work+0x9ba/0x1b20 kernel/workqueue.c:3257 > process_scheduled_works kernel/workqueue.c:3340 [inline] > worker_thread+0x6c8/0xf10 kernel/workqueue.c:3421 > kthread+0x3c5/0x780 kernel/kthread.c:463 > ret_from_fork+0x983/0xb10 arch/x86/kernel/process.c:158 > ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246 > > The buggy address belongs to the object at ffff8880796b0000 > which belongs to the cache kmalloc-8k of size 8192 > The buggy address is located 16 bytes inside of > freed 8192-byte region [ffff8880796b0000, ffff8880796b2000) > > The buggy address belongs to the physical page: > page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x796b= 0 > head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 > anon flags: 0xfff00000000040(head|node=3D0|zone=3D1|lastcpupid=3D0x7ff) > page_type: f5(slab) > raw: 00fff00000000040 ffff88813ff27280 0000000000000000 0000000000000001 > raw: 0000000000000000 0000000000020002 00000000f5000000 0000000000000000 > head: 00fff00000000040 ffff88813ff27280 0000000000000000 0000000000000001 > head: 0000000000000000 0000000000020002 00000000f5000000 0000000000000000 > head: 00fff00000000003 ffffea0001e5ac01 00000000ffffffff 00000000ffffffff > head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000008 > page dumped because: kasan: bad access detected > page_owner tracks the page as allocated > page last allocated via order 3, migratetype Unmovable, gfp_mask > 0xd2040(__GFP_IO|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), > pid 5657, tgid 5657 (dhcpcd-run-hook), ts 79819636908, free_ts > 79814310558 > set_page_owner include/linux/page_owner.h:32 [inline] > post_alloc_hook+0x1af/0x220 mm/page_alloc.c:1845 > prep_new_page mm/page_alloc.c:1853 [inline] > get_page_from_freelist+0xd0b/0x31a0 mm/page_alloc.c:3879 > __alloc_frozen_pages_noprof+0x25f/0x2440 mm/page_alloc.c:5183 > alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2416 > alloc_slab_page mm/slub.c:3075 [inline] > allocate_slab mm/slub.c:3248 [inline] > new_slab+0x2c3/0x430 mm/slub.c:3302 > ___slab_alloc+0xe18/0x1c90 mm/slub.c:4651 > __slab_alloc.constprop.0+0x63/0x110 mm/slub.c:4774 > __slab_alloc_node mm/slub.c:4850 [inline] > slab_alloc_node mm/slub.c:5246 [inline] > __kmalloc_cache_noprof+0x477/0x800 mm/slub.c:5766 > kmalloc_noprof include/linux/slab.h:957 [inline] > kzalloc_noprof include/linux/slab.h:1094 [inline] > tomoyo_print_bprm security/tomoyo/audit.c:26 [inline] > tomoyo_init_log+0xc8a/0x2140 security/tomoyo/audit.c:264 > tomoyo_supervisor+0x302/0x13b0 security/tomoyo/common.c:2198 > tomoyo_audit_env_log security/tomoyo/environ.c:36 [inline] > tomoyo_env_perm+0x191/0x200 security/tomoyo/environ.c:63 > tomoyo_environ security/tomoyo/domain.c:672 [inline] > tomoyo_find_next_domain+0xec1/0x20b0 security/tomoyo/domain.c:888 > tomoyo_bprm_check_security security/tomoyo/tomoyo.c:102 [inline] > tomoyo_bprm_check_security+0x12d/0x1d0 security/tomoyo/tomoyo.c:92 > security_bprm_check+0x1b9/0x1e0 security/security.c:794 > search_binary_handler fs/exec.c:1659 [inline] > exec_binprm fs/exec.c:1701 [inline] > bprm_execve fs/exec.c:1753 [inline] > bprm_execve+0x81e/0x1620 fs/exec.c:1729 > do_execveat_common.isra.0+0x4a5/0x610 fs/exec.c:1859 > page last free pid 5657 tgid 5657 stack trace: > reset_page_owner include/linux/page_owner.h:25 [inline] > free_pages_prepare mm/page_alloc.c:1394 [inline] > __free_frozen_pages+0x7df/0x1160 mm/page_alloc.c:2901 > discard_slab mm/slub.c:3346 [inline] > __put_partials+0x130/0x170 mm/slub.c:3886 > qlink_free mm/kasan/quarantine.c:163 [inline] > qlist_free_all+0x4c/0xf0 mm/kasan/quarantine.c:179 > kasan_quarantine_reduce+0x195/0x1e0 mm/kasan/quarantine.c:286 > __kasan_slab_alloc+0x69/0x90 mm/kasan/common.c:352 > kasan_slab_alloc include/linux/kasan.h:252 [inline] > slab_post_alloc_hook mm/slub.c:4948 [inline] > slab_alloc_node mm/slub.c:5258 [inline] > __kmalloc_cache_noprof+0x274/0x800 mm/slub.c:5766 > kmalloc_noprof include/linux/slab.h:957 [inline] > tomoyo_print_header security/tomoyo/audit.c:156 [inline] > tomoyo_init_log+0x197/0x2140 security/tomoyo/audit.c:255 > tomoyo_supervisor+0x302/0x13b0 security/tomoyo/common.c:2198 > tomoyo_audit_env_log security/tomoyo/environ.c:36 [inline] > tomoyo_env_perm+0x191/0x200 security/tomoyo/environ.c:63 > tomoyo_environ security/tomoyo/domain.c:672 [inline] > tomoyo_find_next_domain+0xec1/0x20b0 security/tomoyo/domain.c:888 > tomoyo_bprm_check_security security/tomoyo/tomoyo.c:102 [inline] > tomoyo_bprm_check_security+0x12d/0x1d0 security/tomoyo/tomoyo.c:92 > security_bprm_check+0x1b9/0x1e0 security/security.c:794 > search_binary_handler fs/exec.c:1659 [inline] > exec_binprm fs/exec.c:1701 [inline] > bprm_execve fs/exec.c:1753 [inline] > bprm_execve+0x81e/0x1620 fs/exec.c:1729 > do_execveat_common.isra.0+0x4a5/0x610 fs/exec.c:1859 > do_execve fs/exec.c:1933 [inline] > __do_sys_execve fs/exec.c:2009 [inline] > __se_sys_execve fs/exec.c:2004 [inline] > __x64_sys_execve+0x8e/0xb0 fs/exec.c:2004 > do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] > do_syscall_64+0xcd/0xf80 arch/x86/entry/syscall_64.c:94 > > Memory state around the buggy address: > ffff8880796aff00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc > ffff8880796aff80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc > >ffff8880796b0000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ^ > ffff8880796b0080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ffff8880796b0100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D > > Fixes: a106e50be74b ("Bluetooth: HCI: Add support for LL Extended Feature= Set") > Reported-by: syzbot+87badbb9094e008e0685@syzkaller.appspotmail.com > Closes: https://syzbot.org/bug?extid=3D87badbb9094e008e0685 > Signed-off-by: Luiz Augusto von Dentz > --- > net/bluetooth/hci_sync.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/net/bluetooth/hci_sync.c b/net/bluetooth/hci_sync.c > index 45d16639874a..f67a32c1451e 100644 > --- a/net/bluetooth/hci_sync.c > +++ b/net/bluetooth/hci_sync.c > @@ -7371,7 +7371,7 @@ static void le_read_features_complete(struct > hci_dev *hdev, void *data, int err) > if (err =3D=3D -ECANCELED) > return; > > - hci_conn_drop(conn); > + hci_conn_put(conn); > } > > static int hci_le_read_all_remote_features_sync(struct hci_dev *hdev, > @@ -7441,7 +7441,7 @@ int hci_le_read_remote_features(struct hci_conn *co= nn) > if (conn->out || (hdev->le_features[0] & HCI_LE_PERIPHERAL_FEATUR= ES)) > err =3D hci_cmd_sync_queue_once(hdev, > hci_le_read_remote_features= _sync, > - hci_conn_hold(conn), > + hci_conn_get(conn), > le_read_features_complete); > else > err =3D -EOPNOTSUPP; > -- > 2.53.0 > > > > -- > Luiz Augusto von Dentz --=20 Luiz Augusto von Dentz